At least 18 people have been infected with hepatitis A following an outbreak caused by contaminated imported frozen berries. Photo: Getty Images

Compensation lawyer Mark O'Connor said consumers should ignore advice to throw out any berries they had purchased, because the product could become key evidence should they contract the virus.

He said people should keep them, but mark the packet with the note "poison" so they're not consumed.

"If they become ill later on, then they will need to be able to prove that they have consumed the product in question and my experience with insurance companies is they won't take your word for it," he said.

A Victorian health department spokesman said there would likely be more cases of the virus coming forward as people learned about the symptoms.

Investigations through our supply chain have identified a specific source of raspberries as a potential common link to the possible safety issues raised by health authorities.

Patties Foods managing director Steven Chaur

"Given the very broad spread of this product, its popularity and its very long shelf life, it's not unexpected that we will get other cases," he said.

Five people have tested positive to hepatitis A in Queensland, along with three from Victoria and two from NSW.

Federal MP Bob Katter said they should sue the federal government, and also vowed to move legislation designed to mandate stricter national labelling standards.

He said infected Australians had a right to be angry after a previous attempt to introduce labelling laws fell flat.

"I think they should be suing the individual ministers who had the proposition put before them and ignored the proposition," he said.

"So they have had flagrant breach of their duty of care and to me they are liable legally."